In Electrolytic Cells, electricity is used to produce chemical changes. As such, we say that electrical energy is being converted into chemical energy.
The reverse occurs in Simple Cells (also commonly known as Electric Cells) whereby chemical changes is used to produce electricity i.e. chemical energy is being converted into electrical energy.
Parts of Simple Cells:
A simple cell consists of two solid electrodes placed in an electrolyte connected together by an electrical conductor such as wire.
The two electrodes must be two different metals.
The electrolyte can be acid solution, alkaline solution, salt solution or even a fruit such as orange or lemon.
The voltage produced depends on the positions of the two metals in the reactivity series. The further away the metals are in the reactivity series, the larger will be the voltage.
For example, magnesium/copper electrodes pair will give a larger voltage than zinc/copper electrodes pair.
How does Simple Cells Work?
Let’s use an example of a simple cell to discuss further.
- Metal electrode 1: Zinc
- Metal electrode 2: Copper
- Electrolyte: Dilute NaCl
The metal which is higher up in the metals reactivity series will be preferentially oxidised. It will release electrons more readily and is the negative electrode (known as Anode). In the above example, zinc is more reactive than copper, thus zinc electrode will be the negative electrode.
The electrons leave the zinc electrode and pass through the connecting wires to the copper electrode.
The metal lower down in the metals reactivity series will become the positive electrode (known as Cathode). As such, copper will be the positive electrode. The electrolyte contains positive ions (sodium cations) and hydrogen ions. Hydrogen ions has a higher ease of discharge as compared to sodium ions and will be preferentially discharged (reduced) by accepting electrons from the negative electrode via the wire.
This a a redox reactions whereby oxidation and reduction reactions occurs simultaneously. Electrons is being transferred from zinc atoms to hydrogen ions.
Uses of Simple Cells:
Simple Cells are commonly also known as batteries which provides a portable form of electrical energy. They supply electricity to watches, torches, etc which do not have to connected to the main electricity supply.
YouTube Video Tutorial on Simple cells in Electrolysis
You can watch the YouTube Video below to have an even clearer idea about Simple Cells.
Length of Video: 11.02 minutes
Direct Video Link: https://www.youtube.com/watch?v=MAwJ2wiIBzo
Do understand the difference between Simple Cells and Electrolytic Cells. Every year, I have a large number of students in my O-Level Chemistry Tuition Class and IP Chemistry Tuition Class who told me that they are confused by their school Chemistry teachers and Chemistry tutors with regards to how the two types of cells work. If you have not read my blog posts regarding Electrolytic Cells, you should do a search for them using the search box at the top right hand corner.
I hope you find the content easy for your understanding and that this article will be part of your Chemistry Notes to master Electrolysis topic.
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Thank you. I am glad you are learning something useful over here 🙂
Hi. I am not sure what you have learned but students should never learn this topic on Electrolysis based on: “Electrolytic Cells is the OPPOSITE of Simple Cells”. This way of surface learning will only results in students being more confused by the concepts required in this application topic. Students should truly understand how an Electrolytic Cell and how a Simple Cell works. This is the only way you can master this topic. QUICK NOTE: Oxidation always occurs at the Anode, while Reduction always occurs at the Cathode. Regardless of whether it’s Electrolytic Cells or Simple Cells. Also, we usually do not memorise anything in this topic. It’s all about understanding and “playing” with the information/diagrams given in the question.
hi i am slightly confused because i was taught in a different way.
when the electrodes are zinc and copper, isn’t the more reactive one made the cathode: so zinc is the cathode?, making copper the anode.
and since it is a simple cell, wouldn’t the reverse take place? [by reverse, i am comparing a simple cell to an electrolytic cell]
so there will be oxidation at the cathode [in an electrolytic cell, oxidation occurs at anode]
and reduction will take place at anode [however, in an electrolytic cell, reduction takes place at anode]
Great website, what are the rules for choosing your electrolyte for a simple cell…..in the zinc /copper cell above is there a salt electrolyte you cannot use?
I would have thought you have to think about using a salt solution that will not react with the zinc. For instance, not silver nitrate because zinc would react with the silver ions directly instead of sending its electrons to the copper electrode because silver is even less reactive than copper…….
Thank you
I appreciate you and the work you do sir
I am glad you have benefitted from the content!
To your Chemistry success, Sean Chua
thank u so much Mr Chua…i’ve learnt and understood the concept